A coaxial coupling of the thermocouple to the magnetic group controlling gas flow in burners

Abstract: The said coupling is fitted at the end of the tube or bipolar electric conductor with a heat insulating head (1) within which there is provided an axial housing for a female terminal (8) terminating the lead wire (9) that lies at the centre of the thermocouple tube, the said head being covered with a metallic sheath (4) that in turn establishes electric continuity with the metallic sheath of the coaxial conductor or tube, which is the electric earth (2) in the thermocouple. It has been specifically designed to electrically connect a thermocouple to the respective magnetic group in a gas tap.

Description: OBJECT OF THE INVENTION The present invention relates to a coupling that has been specifically designed to electrically connect a thermocouple to the respective magnetic group in a gas tap the structural features of which are aimed at achieving a very fast coupling and a high reliability in operation. BACKGROUND OF THE INVENTION It is a known fact that thermocouples used in gas burners are designed to control the general gas flow toward such burners, working with a magnetic group, causing the gas flow to be shut off in the event of the flame being extinguished by accident. More specifically, this magnetic group, that permanently tends to be shut off, must be turned on by hand, operating directly upon a gas tap button, and stays on when the heat generated by the flame causes the thermocouple in turn to generate an electromotive force strong enough to hold the coil in the said magnetic group energised, which status is obviously discontinued when there is no longer an electromotive force upon the extinguishment of the heat source when the burner is switched off. It follows from the above that an electric connection must be provided between the thermocouple and the magnetic group, which is generally a tube that stands as both earth for the said electric connection and shield for a cable coaxially housed within it, duly electrically insulated from the surrounding tube or earth. Nowadays, in order to electrically connect the thermocouple bipolar conductor to the magnetic group, the said conductor ends in a threaded connector secured to a lock nut established in the magnetic group, cf. US-A-2 503 459. According to US-A-2 379 712 the earth conductor is welded to a connector element which is screwed onto the gas tap housing. This threaded coupling operation is clearly slow and sometimes complicated, above all when the position of the magnetic group is such that access to the connection area is difficult, the space available to such end being small, such as, for instance, with extra-slim worktops. DESCRIPTION OF THE INVENTION The fast coupling subject of the invention has been designed to fully solve the above problems and relies essentially on a coupling by simple axial plugging, whereby operation is extremely fast and simple, indeed almost instantaneous. More specifically and in order to achieve the above, the features of the coaxial coupling subject hereof lie in providing the end of the tube or bipolar electric conductor with a preferably resilient and basically cylindrical heat insulating head having a large diameter, within which there is established an axial housing for a female terminal found at the end of the lead wire lying at the centre of the thermocouple tube, the said head being moreover covered with a metallic sheath that in turn establishes electric continuity with the metallic sheath of the coaxial conductor or tube, being earth in the thermocouple. This head, the axial bore in which also opens toward its free end to receive a corresponding male terminal associated to the magnetic group, is fitted at that same end with an annular housing of considerable depth into which a collar projecting from the front of the magnetic group can be "plugged". The said collar is threadedly engaged to the magnetic group body and the latter is fitted with an electrically insulating packing supporting the male terminal and providing an optimal structural stiffness, contemporaneously ensuring a good electric contact. More specifically, the said terminal is hollow, the end of the solenoid conductor is housed in its through bore and the said terminal and conductor are definitively locked together by a spot weld at the common and free end of both elements. DESCRIPTION OF THE DRAWINGS In order to provide a fuller description and contribute to the complete understanding of the characteristics of this invention, a set of drawings is attached to the specification which, while purely illustrative and not fully comprehensive, shows the following: Figure 1.- Is a diagrammatic side elevation and diametric sectional view of an axial coupling of the thermocouple to the magnetic group controlling the flow of gas in burners, the two parts of the coupling being shown disengaged so that their structure may be more clearly shown. Figure 2.- Is the same assembly of the above figure, now engaged. PREFERRED EMBODIMENT OF THE INVENTION The figures show that the coaxial coupling subject hereof starts with the provision of a head (1) made of electrically insulating material, which is preferably plastic, to cover the end of the conductor (2) through which the thermocouple is to be coupled and connected to the magnetic group (3) mounted upon a gas tap (3'), the said head (1) having a considerable diameter and carrying a sheath (4) that is by nature metallic and conducts electricity, and making up an extension through a neck (5), without interruption, of the conductor (2) earth (6). The said head (1) is fitted with an axial bore (7) which houses and stabilises a female terminal (8) duly connected to the conductor (2) phase (9), the said axial bore (7) being capable of receiving at its free end (10) the corresponding male terminal (11) associated to the magnetic group (3). More specifically, the front end of the magnetic group body (3), being at the same time its earth, is threadedly engaged to a collar (12), being metallic by nature and having an external diameter suited to the internal diameter of the sheath (4) in the head (1), with which it establishes electric continuity in the engaged status shown in figure 2, the said collar (12) being further useful as a means of attachment for the packing supporting the said male terminal (11). More specifically and as shown in any of the figures, in particular figure 1, the said collar (12) acts as an element to hold an internal centre plate (13), electrically insulating by nature, that in turn supports the terminal (11) with the assistance of a pair of internal rings (14-14'), its base being axially crossed by a straight extension (15) of the conductor making up the solenoid (16) in the magnetic group, the terminal (11) being hollow and axially traversed by the said straight extension (15) of the conductor, these elements being fixed at their free end and by a spot weld (17) that ensures a smooth electric continuity at the coupling of the male terminal (11) within the female terminal (10). It follows from the figures that the magnetic group (3) comprises the centre plate (13), the solenoid (16) and the very platelet (18) drawn by the solenoid (16). This platelet is associated to the gas tap (3') seal (19). We feel that the description need not be extended any longer for any expert in the art to have grasped the full scope of the invention and the advantages it offers. The materials, shape, size and layout of the elements may be altered provided that this entails no modification of the essential features of the invention. The terms used to describe the invention herein should be taken to have a broad rather than a restrictive meaning.

Claims: A coaxial coupling of a flame sensing thermocouple to the magnetic group (3) of a gas tap controlling gas flow in a burner, characterised in comprising a cylindrical head (1) made of electrically insulating material, connected to the free end of a thermocouple phase conductor (9), the head having a metallic sheath (4) establishing electric continuity with a conductor earth element (2), the said head having inside a female terminal (8) duly connected to the thermocouple phase conductor (9), the said female terminal being designed to receive by plugging a corresponding male terminal (11) associated to the magnetic group (3) in a magnetic group housing and that is attached to said magnetic group with the assistance of a metallic collar (12) that, in addition to making up the mechanical means of attachment for such male terminal through the respective packing, extends to form a front neck for coupling by plugging to the metallic sheath (4) in the head (1), to establish electric continuity between the earth of the head and the magnetic group housing. A coaxial coupling of the thermocouple to the magnetic group controlling gas flow in burners, as in claim one, characterised in that the said metallic collar (12) is coupled to the magnetic group (3) inserting a sort of centre plate (13) that is electrically insulating by nature, within which there is provided a pair of rings (14,14') working in the packing axially fitting the male terminal (11), the said male terminal being provided to be hollow and a straight extension of the conductor making up the magnetic group solenoid at the bottom of the said electrically insulating centre plate (13) axially crossing the male terminal and being fitted at its free end to the free end of the latter by means of a spot weld (17) that ensures a smooth electric continuity.

Inventors: GUIRADO TRISTAN JOSE ANTONIO O, GUIRADO TRISTAN                                  A, Guirado Tristan, José Antonio ORKLI, S. COOP. LTDA
Applicants: ORKLI S COOP LTDA, ORKLI S. COOP. LTDA.
Application year: 1994
Main classification: F23N5
IPC codes: F23N5